Lean Problem
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 6,252
Likes: 2
From: Silicon Valley Kalifornia
Lean Problem
Ok, here goes. If the car sits for a long time (days), the car starts fine...warms up...runs at a perfect/approx. 14.7:1....although the headers get cherry red at about 2000rpm.
Ok, next day, start the motor, warms up and goes to 15:1...16:1...17:1....18:1. That's when I shut the motor off.
I have swapped ECMs. Has a new MAF. Fuel pressure is adjusted.
Timing set. Everything is pretty much new or verified.
Anyone care to comment? TIA!
Ok, next day, start the motor, warms up and goes to 15:1...16:1...17:1....18:1. That's when I shut the motor off.
I have swapped ECMs. Has a new MAF. Fuel pressure is adjusted.
Timing set. Everything is pretty much new or verified.
Anyone care to comment? TIA!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
What year? Modified MAF/throttle body? How are you measuring fuel ratio? Off hand, injectors may need cleaning or there's a header/vacuum leak, but these are just guesses. What do the block learn cells look like at 2000 rpms? Is the lean condition unique to one side?
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 6,252
Likes: 2
From: Silicon Valley Kalifornia
Its a 1985. AFR meter is measuring off a welded bung about 4 inches downstream of stock O2 sensor. Both sides of exhaust read the same.
Would a vacuum or exhaust leak cause this? ...but it runs fine if it sits for a long time.
Would a vacuum or exhaust leak cause this? ...but it runs fine if it sits for a long time.
